Glossary

[UNDER CONSTRUCTION] This Glossary is derivitive from the 9th Edition of the BIF Guidelines for Uniform Beef Improvement book, which attributed the original work to John Hough, EPD International and Ronnie Silcox, University of Georgia

A

Average daily gain

ADG

Measurement of the average daily body weight change over a specified period of time of an animal on a feed test.

B

Backcross

The mating of a two-breed crossbred individual back to one of its parental breeds. Example: A Hereford-Angus crossbred cow bred back to an Angus bull.

Base pair

The complementary bases found within a DNA molecule. There are four different bases: adenine (A), thymine (T), cytosine (C), and guanine (G). A always pairs with T, and C always pairs with G. The base sequence ultimately determines the effect of the gene.

Beef carcass data service

A program whereby producers, for a fee, can receive carcass evaluation data on their cattle by using a special carcass data ear tag for their slaughter animals. See county extension director, breed representative, Beef Cattle Improvement Association representative, or area office of USDA meat grading service for information.

Beef Improvement Federation

BIF

A federation of organizations, businesses, and individuals interested or involved in performance evaluation of beef cattle. It seeks to build confidence of the beef industry in the principles and potentials of performance testing. The purposes of BIF are to achieve utilization of the most efficient and effective performance evaluation methods, uniformity of procedures, development of programs, cooperation among interested entities, and education of its members.

Best linear unbiased prediction

BLUP

A genetic prediction methodology providing the most accurate and precise genetic evaluations possible, given the information and family structure that are available.

Biological type

A group of cattle breeds having a similar geographic origin and past selection history and with similar genetic potential for traits of economic importance. British general purpose beef cattle breeds, for example, have genetic potential for moderate growth, muscling, and milk yield; whereas continental European dual-purpose breeds have genetic potential for high milk yield and rapid growth.

Birth weight

BW

The weight of a calf taken within 24 hours after birth. Heavy birth weights tend to be correlated with calving problems, along with other factors.

Body capacity

A subjective assessment of the feed intake capacity of an individual or breed, typically assessed by visually evaluating body length, body depth, and spring of ribs.

Body condition score

A score on a scale of 1 to 9, reflecting the amount of fat reserves in a cow's body, where 1 = very thin and 9 = extremely fat.

Bos indicus

A subspecies of cattle of south Asian origin. Often known as Zebu, they have prominent humps forward of the shoulder. The Brahman breed is one example in the United States.

Bos taurus

A subspecies of cattle of western Asian origin but often referred to as "European". Most breeds commonly found in the United States and Canada, and their European ancestors, belong to this group. Bos indicus x Bos taurus crosses are viable and fully fertile and exhibit large amounts of heterosis.

Breed

Animals with a common origin and selection history. Animals within a breed have physical characteristics that distinguish them from other breeds or groups of animals within that same species.

Breed association

An organization that maintains pedigree and performance information and arranges for timely genetic evaluation of animals within that breed. Breed associations also establish regulations for registration of animals, promote the breed, and advance the interests of the breeder members.

Breeding objective

The goal of a breeder's selection program, for example to produce high quality, lean meat at lowest cost. It may also include a listing of economically related traits to be used as selection criteria to achieve the overall goal. Objectives may vary among breeders due to their genetic and physical resources and their markets.

Breeding soundness examination

Inspection of a bull, including evaluation of physical conformation and soundness through genital palpation, scrotal circumference assessment, and testing of semen for motility and morphological abnormalities.

Breeding value

Transmissible genetic merit of an individual, or the value of that individual as a parent. In the United States and Canada, genetic predictions are expressed as progeny differences rather than as breeding values. Because any parent contributes only half the genes in any one offspring, the progeny difference of an individual is half its breeding value.

British breeds

Breeds of cattle such as Angus, Hereford, and Shorthorn originating in Great Britain.

C

Caesarean section

A process in which the calf is surgically removed from the cow during parturition by making a large incision in the right side of the cow just above the flank.

Calving difficulty (Dystocia)

Abnormal or difficult labor, causing difficulty in delivering the fetus and/or placenta. Difficult births lead to increased calf and cow mortality and to more difficult rebreeding of the cow.

Calving ease

The opposite of calving difficulty. An easy calving is one that does not require assistance and does not impose undue strain on the calf or dam.

Calving ease score

A numerical score quantifying calving ease, ranging from 1 for an easy, unassisted calving through 5 for an abnormal presentation.

Calving season

The season(s) of the year when the calves are born. Limiting calving seasons is the first step to performance testing the whole herd, accurate records, and consolidated management practices.

Carcass evaluation

Techniques for measuring components of quality and quantity in carcasses and using the information for genetic prediction of carcass merit.

Carcass merit

Desirability of a carcass relative to quantity of components (muscle, fat, and bone), USDA quality grade, and potential eating quality.

Carcass quality grade

An estimate of palatability based primarily on marbling and maturity and generally to a lesser extent on color, texture, and firmness of lean.

Carrier

An individual that is heterozygous, having one dominant and one recessive allele at a given locus. For example, an animal with one gene for polledness and one gene for horns will be polled but can produce horned offspring when mated to another animal carrying the gene for horns.

Central test

A comparison conducted at a single location where animals are assembled from several herds to evaluate differences in performance traits under uniform management conditions.

Chromosome

Chromosomes are paired strands of DNA, with accompanying structural proteins, on which genes are located. Domestic cattle have 30 pairs of chromosomes, one chromosome of each pair having been inherited form each parent. One random chromosome of each pair is transmitted to each egg or sperm cell produced by a parent.

Closed herd

A herd in which no outside breeding stock (cattle) are introduced.

cM (centiMorgan)

The unit of length used to express locations of genes on chromosomes. One cM is approximately one million nucleotides long. The entire length of the DNA within a cattle cell is approximately 3000 cM. A gene ranges from .001

Codon

A specific three

Collateral relatives

Relatives of an individual that are not its ancestors or its descendants. Brothers and sisters are an example of collateral relatives.

Commercial producers

Producers whose primary goal is to produce animals for herd replacement, feeding, and slaughter rather than breeding stock for sale to other producers. Progressive commercial producers seek bulls or semen from seedstock breeders that have comprehensive programs designed to produce animals with optimum genetic merit for the combination of traits that increase efficiency and profit of their production system.

Compensatory gain

Rapid, subsequent gain of cattle that have been nutritionally deprived for some portion of their life.

Composite breed

A breed made up of combinations of other breeds.

Complementarity

The combining of breeds or individual animals that have characteristics that complement each other, thereby obtaining optimum progeny.

Complementary DNA (cDNA)

A DNA copy made from RNA through reverse transcription.

Conformation

A description of the shape of body parts of an animal.

Congenital

A condition that was acquired during prenatal life and therefore exists at or dates from birth. The term is often used in the context of defects present at birth.

Contemporary group

A group of cattle that are of the same breed and sex, are similar in age, and have been raised in the same management group (same location on the same feed and pasture). Contemporary groups should include as many cattle as can be accurately compared.

Continental (European) breed

Breeds originally developed on the continent of Europe. Examples include Simmental, Limousin and Charolais.

Correlation

A numerical measure, ranging between

Crossbreeding

The mating of animals of different breeds or subspecies, frequently resulting in heterosis (hybrid vigor) for many economically important traits.

Culling

The process of eliminating less productive or less desirable individuals from a herd.

Cutability

An estimate of the percentage of salable meat (muscle) from a carcass versus percentage of waste fat. Percentage retail yield of carcass weight can be estimated by a USDA prediction equation that includes measured or estimated values for hot carcass weight, rib eye area, fat thickness, and estimated percent of kidney, pelvic, and heart fat.

D

Decision Evaluator for the Cattle Industry (DECI)

A decision support system available through the U.S. Meat Animal Research Center that simulates the impact of alternative breeding or management strategies on production and profit within a producer's herd.

Decision Support System (DSS)

A set of rules, usually coded into a computer program, that helps a producer evaluate the impact of alternative breeding or management strategies on one or more aspects of a beef production enterprise.

Deviation

The difference between an individual record and the average for that trait in the individual's contemporary group. For all animals within a contemporary group, these differences sum to zero when the correct average is used. A ratio deviation is an individual's ratio minus the group average ratio or 100 when expressed in percentage units.

Direct effect

For weaning weight that portion of preweaning growth that is due to the calf's genetics (see Maternal Effect).

Direct EPD

An EPD representing the effect of the individual's own genes on the trait of interest. A calving ease direct EPD, for example, represents calving ease of an individual's progeny. See also Maternal EPD.

Disposition (temperament)

A measure of an animal's docility, wildness, or aggression toward unfamiliar situations, human handlers, or management interventions.

DNA (Deoxyribonucleic acid)

The chemical compound that stores within each cell genetic information unique to an individual. A DNA molecule is composed of two strands of nucleotides bound to one another by chemical bonds between each complementary (A

Dominant

An allele is dominant when its presence prevents a recessive allele from affecting the phenotype of an individual heterozygous at the locus in question. For example, the allele for polledness (P) is dominant to the allele allowing growth of horns (p), so an animal with the genotype Pp will have the polled form of the trait.

Double muscling

A simply inherited trait evidenced by an enlargement of the muscles with large grooves between the muscle systems especially noticeable in the hind leg.

Dressing percentage

(Chilled carcass weight/live weight) x 100.

Dystocia (calving difficulty)

Abnormal or difficult labor causing difficulty in delivering the fetus and/or placenta. Difficult births lead to increased calf and cow mortality and to more difficult rebreeding of the cow.

E

Economic value

The net return for a one unit change (pound or percentage, for example) for an economically important trait under selection.

Economically relevant trait

ERT

Any trait that is directly associated with income or costs in a specific production system.

Traits that are of direct economic importance to cattle producers.

Effective progeny number (EPN)

An indication of the amount of information available for estimation of expected progeny differences (EPDs) in cattle evaluation. It is a function of number of progeny of a parent but is adjusted for their distribution among herds and contemporary groups and for the number of contemporaries by other sires. EPN is less than the actual number of progeny because the distribution of progeny is never ideal.

Electrophoresis

A process used to separate DNA fragments by length. DNA fragments are placed at the top of a gel matrix that is then exposed to an electrical current. This causes fragments to migrate through the pores in the gel at rates proportional to fragment size. Resulting fragment location on the gel can be visualized by appropriate labeling techniques.

Embryo transfer

Removing fertilized ova (embryos) from one cow (the donor), generally in response to hormone

Environment

All external (nongenetic) conditions that influence the reproduction, production, and carcass merit of cattle. When environmental influences on phenotypic merit are not properly be accounted for in genetic evaluations, they reduce the accuracy of breeding value estimation and of subsequent selection.

Estimated breeding value (EBV)

An estimate of an individual's true breeding value for a trait based on the performance of the individual and close relatives for the trait itself and sometimes performance of genetically correlated traits. EBV combines available performance information on the individual and sibs and the progeny of the individual and other relatives. Expected progeny differences (one

Exon

Those regions of a gene in which the nucleotide sequence actually codes for a biologically relevant product.

Expected Progeny Difference (EPD)

The difference in expected performance of future progeny of an individual, compared with expected performance at some base point for the population (e.g., the average EPD is 0). The base point may either be fixed or floating. A fixed base sets the average EPD to 0 at a specific point in time (e.g., a specific year). A floating base point changes over years as the number of records analyzed increases. Fixed base points are recommended, especially for traits that have intermediate optima. EPDs are estimated from phenotypic merit of an individual and all of its relatives and are estimates of one

I

Indicator trait

Any trait that is not associated with income or costs in a production system but is (genetically) correlated to an economically relevant trait.